Yes your correct! In inches.some tire sizes say things like 33/12.50R15LT. this is a 33in tire thats 12.5 wide for a 15 in rim correct?
Your close. The second number is the "aspect ratio", meaning that the sidewall height is 70% of the Tire width. Here is a pretty good calculator to compare tire sizes...Wheel / tire size calculator / comparer - RIMS-N-TIRESYes your correct! In inches.
the 285/70/R17 is in metric
285- tire width
70 - sidewall height
R - Radial
17 rim height (in inches)
The only thing weird is the second number some how is a percentage of the tire width